EESDL
Quite a good insight into corporate work.
You are right on the money as far as correcting invoice errors, almost every maintenance invoice we had was wrong in some way, one was a plausible 20K ended up being £250.
With regards to
I have found that lesser-experienced pilots tend to be more malleable by irate owners.....exactly what not is required in certain scenarios, I would suggest.
I was asked by a relatively inexperienced friend who was given a job flying day VFR corporate in a single to draw up 'How to be a corporate pilot' document. It had a bit in it that amounted to 'you have to be willing to stick to your decisions in the knowledge that even if you are right it might cost you your job', two years later it cost me mine, but I'd still make the same decision again.
The corporate world
can be fickle and often principals just want to get there and if they think someone else might do it when you refuse (for whatever reason and however nicely or reasonably) you'll be gone in a blink.
I know of one talented pilot who was undercut by a fill in pilot and was gone by the end of the month.
The Train To Gain thing is handy to know.
GS